US4813654A - Annealing furnace base construction - Google Patents

Annealing furnace base construction Download PDF

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Publication number
US4813654A
US4813654A US07/118,857 US11885787A US4813654A US 4813654 A US4813654 A US 4813654A US 11885787 A US11885787 A US 11885787A US 4813654 A US4813654 A US 4813654A
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United States
Prior art keywords
base
annular
top plate
partitions
heat treating
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Expired - Fee Related
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US07/118,857
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English (en)
Inventor
John E. Singler
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CLIMATRON CORP
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Lee Wilson Engineering Co Inc
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Priority to US07/118,857 priority Critical patent/US4813654A/en
Assigned to LEE WILSON ENGINEERING COMPANY, INC., A CORP. OF OHIO reassignment LEE WILSON ENGINEERING COMPANY, INC., A CORP. OF OHIO ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SINGLER, JOHN E.
Priority to CA000579384A priority patent/CA1315540C/fr
Application granted granted Critical
Publication of US4813654A publication Critical patent/US4813654A/en
Assigned to CLIMATRON CORP. reassignment CLIMATRON CORP. NUNC PRO TUNC ASSIGNMENT (SEE DOCUMENT FOR DETAILS). EFFECTIVE ON 03/12 Assignors: LEE WILSON ENGINEERING COMPANY, INC.
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Expired - Fee Related legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/663—Bell-type furnaces
    • C21D9/673—Details, accessories, or equipment peculiar to bell-type furnaces

Definitions

  • This invention relates to metallurgical processes, and especially to the construction of a heat treating furnace for annealing coils of metal strip. More particularly, the invention relates to an annealing furnace base that (1) provides thermal insulation between the sealed heat treating compartment and the surrounding atmosphere and (2) supports both the coil or coils of metal strip and a blower wheel and diffuser structure.
  • the steel strip may be heated to as high as 1650° F.
  • Other treatments may involve modifying the chemical composition of the metal.
  • the carbon content of steel strip may be modified by the use of a suitable gas.
  • treatments may involve oxidation, bright annealing, gas alloying, and the application to the surface of materials that will react with the constituents of the metal.
  • the inert gas used in the annealing process is confined with the coils in a sealed annealing compartment enclosed by a portable inner cover that surrounds the coil or coils with its top and sides and that engages a sealing means at the bottom of the side walls.
  • the inner cover is surrounded by a portable bell that includes internal heating means or burners to heat the inner cover and the gas therein, and that insulates the inner cover from the surrounding atmosphere outside the furnace.
  • the floor of the sealed compartment is defined by an insulating base that serves both to insulate the sealed compartment from the surrounding external support structure and to support the coil or coils to be annealed, along with a blower wheel and diffuser structure located between the base and the bottom of a coil.
  • the gas is circulated by a centrifugal blower located in the blower housing and a surrounding diffuser structure directs the hot gas in a somewhat tangential path to the side walls of the compartment where the gas proceeds upward to the top and then downward through the central axial opening in the coils.
  • the furnace design must provide a support structure or base capable of supporting great weight particularly in view of the tremendous weight of the coils of steel strip. For this reason, it is desirable to minimize the weight of the furnace components as much as possible.
  • furnace components serve primarily an insulating function, and their weight may be minimized by using the lightest possible insulating material that still provides the desired thermal insulating properties.
  • the furnace base must have great strength in order to support the coils, blower housing, and diffuser structure. Accordingly, most lightweight insulating materials would not provide the compressive strength required by the base.
  • the furnace base has usually been constructed of steel exterior members to define an enclosure, and the enclosure was filled with a high strength, solid, castable ceramic material.
  • the castable material is by nature quite heavy, and thus inconsistent with the goal of minimizing weight.
  • this base construction resulted in a need for a time-consuming dry-out procedure prior to each annealing operation.
  • top plate of the enclosed base in prior art constructions is exposed to great thermal stresses caused by thermal expansion and contraction during the annealing process. These stresses cause fatigue that reduces the effective life of the base and presents a danger of failure that could cause leakage of gas into and out of the sealed annealing compartment.
  • the annealing furnace base construction of the present invention reduces the difficulties indicated above, and affords other features and advantages heretofore not obtainable.
  • Another object of the invention is to minimize the stresses caused in the upper plate of an annealing furnace base, the stresses being those caused by thermal expansion and contraction during the annealing process.
  • Still another object of the invention is to eliminate the need for using a heavy, castable, ceramic material in the annealing compartment base of a heat treating furnace.
  • the base is uniquely suited for use in annealing coils of steel strip using the process whereby the strip is placed in a sealed compartment through which a hot, inert gas is circulated.
  • the base defines the bottom of the sealed compartment, and is adapted to support thereon a blower housing and diffuser structure on which the coils of steel strip are placed.
  • the base forms part of the sealed compartment in that the side walls are sealed relative to the base in such a way that intrusion of outside atmosphere or escape of inside atmosphere from the annealing compartment is prevented.
  • the base comprises a top plate, a floor, and side walls to define therein a sealed enclosure.
  • a plurality of radially spaced, annular, concentric bearing partitions adapted to slidingly engage and support the top plate in a manner to promote sliding movement of the top plate thereon in response to thermal expansion and contraction.
  • the partitions define with the side walls of the enclosure interior spaces that are filled with a lightweight, thermal insulating material.
  • the top plate assembly comprises at least two circular sections located one within the other.
  • the joint between the two sections comprises an annular expansion joint that seals the space between the two sections.
  • the joint has a "U" shape when viewed in cross section so that any radial expansion or contraction of the two sections relative to one another is accommodated by the annular expansion joint.
  • arcuate pad segments are secured to the top of the corrugated partitions to provide a plurality of concentric annular rings or pads, the top surfaces of which slidingly engage the bottom surfaces of the sections of the top plate assembly.
  • FIG. 1 is a vertical section through a heat treating furnace adapted to anneal coils of steel strip and which utilizes an annealing compartment base embodying the present invention
  • FIG. 2 is a broken sectional view on an enlarged scale of certain components of the annealing furnace of FIG. 1;
  • FIG. 3 is a horizontal section taken on the line 3--3 of FIG. 2, with parts broken away for the purpose of illustration and showing the construction of the annealing compartment base of the invention;
  • FIG. 4 is a sectional view on an enlarged scale, taken on the line 4--4 of FIG. 2 and illustrating the annealing compartment base of the invention, with the furnace bell and the inner cover removed;
  • FIG. 5 is a fragmentary, sectional view showing the thermal expansion joint between the two circular sections of the top plate of the annealing compartment base of the invention.
  • FIG. 1 there is shown a heat treating furnace 10 for use in annealing a plurality of coils 11, 12, 13, and 14 of metal strip supported in the furnace in a vertical axis orientation one-on-top-of-the-other.
  • the annealing is accomplished by circulating a hot inert gas to heat the strip.
  • the furnace includes a removable outer cover or bell 20, a removable inner cover 30, and an insulating base 50 that is sealingly connected to the lower edges of the side walls of the inner cover to define a sealed annealing compartment 40.
  • the base 50 serves both to insulate the annealing compartment 40 from the surrounding support structure and to support the weight of the coils 11, 12, 13, and 14.
  • a centrifugal blower 16 is located in the blower housing 15 and is adapted to force the inert gas in a tangential direction guided by diffuser vanes 17 toward the outer wall of the annealing compartment 40.
  • the centrifugal blower 16 is driven by a blower motor 18 located below the base 50 and which has a motor shaft 19 that extends upward through the base 50 to the blower 16.
  • the outer cover or bell 20 has insulated walls 21 and a top 22 that are formed at least in part of thermal insulating material and rest on a support structure 23.
  • the bell 20 also has a lifting eye 24 to permit the entire outer cover or bell to be lifted upward away from the inner cover and its contents to permit loading and unloading of the coils.
  • a number of radiant burner tubes 25 and 26 are located between the inside face of the outer walls 21 and the inner cover 30 for use in heating the inner cover and the inert gas contained therein to the desired annealing temperature.
  • the inner cover 30 comprises a cylindrical side wall 31 and a circular top 32, which also has a lifting eye 33 for use in removing the inner cover and replacing it over the coils to be annealed.
  • the lower portion of the cylindrical side wall 31 has a pair of annular concentric seal flanges 35 and 36 connected by a web 37 that rests on an annular support wall 38 extending upwardly from the support structure.
  • the annular support wall is located in an annular channel or trough 39 which, depending on recommended design. is filled with sand or water, for example, to seal the bottom of the inner cover 30 from the surrounding atmosphere. This prevents intrusion of outside oxygen-containing atmosphere to the annealing compartment, and also prevents escape of the inert gas from the annealing compartment to the outside atmosphere.
  • the inert gas is driven by the centrifugal blower 16 toward the annular space adjacent the inner wall of the inner cover, and thus upward to the top of the annealing compartment and above the uppermost coil 11.
  • the gas returns to the blower through the central opening through the coils.
  • the base 50 rests on the support structure on which the bell rests, and also is sealingly connected to the trough 39 in which the inner cover is sealed. Accordingly, the inner cover and the base 50 define the sealed annealing compartment 40.
  • the base must insulate the annealing compartment from the surrounding structure in the same way that the bell 20 insulates the interior of the furnace from the surrounding atmosphere. Also, the base 50 must have sufficient strength to support the blower housing and diffuser as well as the coils 11, 12, 13, and 14.
  • the base 50 comprises an annular bottom plate 51, a frustoconical side wall 52, and a top plate assembly 80.
  • the bottom plate 51 and the top plate assembly 80 have central openings 55 and 56, respectively, to receive a shaft bushing 57 through which the shaft 19 of the blower motor 18 extends. This is best shown in FIGS. 3 and 4.
  • the bottom plate 51 rests on several support beams such as the steel I-beams 59 shown in FIG. 4, as well as on other support structure.
  • a pair of radially extending distributor tubes 53 and 54 extend from the shaft bushing 57 radially outward and then upward through openings in the top plate assembly 80 to accommodate pressure variations that occur during blower operations.
  • annular corrugated metal partitions 60 through 67 Located within the base 50 and welded to the bottom plate 51 are eight annular corrugated metal partitions 60 through 67 that are located vertically in a concentric pattern extending from the innermost to the outermost in a uniformly spaced pattern.
  • the partitions define annular spaces between them which are filled with a thermal insulating material such as granular material or other suitable ceramic material of light weight and which need not bear any load.
  • the load is transmitted from the top plate assembly 80 to the bottom plate 51 by the annular corrugated partitions.
  • arcuate pads 68 On top of the partitions are arcuate pads 68 that are arranged end-to-end in a circular pattern around the top of each annular partition to form a circular bearing surface.
  • the pads are adapted to accommodate sliding movement of the top plate assembly 80 in radial directions caused by thermal expansion and contraction during the annealing process.
  • the partitions are spaced from one another a desired distance by means of a plurality of spacer tubes 69 that extend between the bottom plate and the top plate assembly 80 to assure rigidity and uniformity of spacing. Also, drain tubes 75,76 are located at the bottom of the base to permit any moisture that accumulates in the interior to be drained away.
  • the top plate assembly 80 comprises an annular inner section 81 and a larger diameter outer section 82. These sections 81 and 82 are concentric and spaced from one another to define an annular gap. The plates are connected to one another in the annular gap by a U-shaped annular expansion joint 85.
  • the expansion joint is welded to the respective circular edges of the sections 81 and 82 and, because of its U-shaped configuration, is capable of accommodating relative movement between the sections that would tend to decrease or enlarge the gap at the joint between the two sections. Accordingly, thermal expansion and contraction that occur during the annealing process are accommodated in a manner that reduces thermal stresses and prevents warping, etc. of the sections as might otherwise occur in the annealing process.
  • Passages 86 and 87 are provided in the base 50 for the initial evacuation of oxygen-containing atmosphere from the annealing compartment and for the introduction of the inert gas atmosphere.
  • the annealing furnace base construction of the present invention (1) provides sufficient strength to support the required load, (2) provides the required thermal insulation with minimal weight, (3) accommodates thermal expansion and contraction that occur at the floor surface of the annealing compartment, and (4) eliminates the need for an initial dry-out procedure as required in the case of conventional or castable ceramic base constructions.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
US07/118,857 1987-11-09 1987-11-09 Annealing furnace base construction Expired - Fee Related US4813654A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US07/118,857 US4813654A (en) 1987-11-09 1987-11-09 Annealing furnace base construction
CA000579384A CA1315540C (fr) 1987-11-09 1988-10-05 Base pour four de recuit

Applications Claiming Priority (1)

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US07/118,857 US4813654A (en) 1987-11-09 1987-11-09 Annealing furnace base construction

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US4813654A true US4813654A (en) 1989-03-21

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5006064A (en) * 1989-12-28 1991-04-09 Alloy Engineering Company Furnace seal
WO1993021352A1 (fr) * 1992-04-13 1993-10-28 Loi Essen Industrieofenanlagen Gmbh Four a recuire a cloche
EP0728848A3 (fr) * 1995-02-24 1996-10-23 Ebner Peter H Embase pour four à cloche
US6063331A (en) * 1998-04-28 2000-05-16 Rad-Con Incorporated Annealing furnaces
US6210499B1 (en) * 1998-10-05 2001-04-03 Peter Ebner Method of bright annealing metals having a high affinity to oxygen
US20060196399A1 (en) * 2005-03-02 2006-09-07 Hatch Ltd. Split shell circular furnace and binding systems for circular furnaces
US7427375B1 (en) 2005-08-29 2008-09-23 Mnp Corporation Diffuser for an annealing furnace
CN101845544A (zh) * 2010-05-22 2010-09-29 奉化市光亮热处理电炉有限公司 具有防止炉胆变形的退火炉
CN103395975A (zh) * 2013-07-31 2013-11-20 中国建材国际工程集团有限公司 一种玻璃退火窑侧墙保温棉模块化填充方法
WO2016012860A1 (fr) * 2014-07-24 2016-01-28 Sabic Global Technologies.B.V. Acier laminé à froid recuit et son procédé de préparation

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2414996A (en) * 1945-02-01 1947-01-28 Wilson Eng Co Inc Lee Charge support for the base of cover-type furnaces
US2504809A (en) * 1945-10-26 1950-04-18 Carnegie Illinois Steel Corp Annealing stand construction
GB878497A (en) * 1957-02-13 1961-10-04 Lee Wilson Method of and apparatus for annealing strip metals
CA630356A (en) * 1961-11-07 Lee Wilson Coil support for open coil annealing
US3879167A (en) * 1974-04-18 1975-04-22 Jones & Laughlin Steel Corp Non-warping heat shield
US4023782A (en) * 1974-09-06 1977-05-17 S.A. Des Anciens Etablissements Paul Wurth Tuyere stock and compensator joint therefore

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA630356A (en) * 1961-11-07 Lee Wilson Coil support for open coil annealing
US2414996A (en) * 1945-02-01 1947-01-28 Wilson Eng Co Inc Lee Charge support for the base of cover-type furnaces
US2504809A (en) * 1945-10-26 1950-04-18 Carnegie Illinois Steel Corp Annealing stand construction
GB878497A (en) * 1957-02-13 1961-10-04 Lee Wilson Method of and apparatus for annealing strip metals
US3879167A (en) * 1974-04-18 1975-04-22 Jones & Laughlin Steel Corp Non-warping heat shield
US4023782A (en) * 1974-09-06 1977-05-17 S.A. Des Anciens Etablissements Paul Wurth Tuyere stock and compensator joint therefore

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5006064A (en) * 1989-12-28 1991-04-09 Alloy Engineering Company Furnace seal
WO1993021352A1 (fr) * 1992-04-13 1993-10-28 Loi Essen Industrieofenanlagen Gmbh Four a recuire a cloche
CN1101926C (zh) * 1995-02-24 2003-02-19 彼得·H·埃布纳 罩式退火炉的退火炉台
EP0728848A3 (fr) * 1995-02-24 1996-10-23 Ebner Peter H Embase pour four à cloche
US5616297A (en) * 1995-02-24 1997-04-01 Ebner Peter H Annealing base for hood-type annealing furnaces
AT402508B (de) * 1995-02-24 1997-06-25 Ebner Peter H Glühsockel für haubenglühöfen
US6063331A (en) * 1998-04-28 2000-05-16 Rad-Con Incorporated Annealing furnaces
US6210499B1 (en) * 1998-10-05 2001-04-03 Peter Ebner Method of bright annealing metals having a high affinity to oxygen
US20060196399A1 (en) * 2005-03-02 2006-09-07 Hatch Ltd. Split shell circular furnace and binding systems for circular furnaces
US8245653B2 (en) * 2005-03-02 2012-08-21 Hatch Ltd. Split shell circular furnace and binding systems for circular furnaces
US7427375B1 (en) 2005-08-29 2008-09-23 Mnp Corporation Diffuser for an annealing furnace
CN101845544A (zh) * 2010-05-22 2010-09-29 奉化市光亮热处理电炉有限公司 具有防止炉胆变形的退火炉
CN103395975A (zh) * 2013-07-31 2013-11-20 中国建材国际工程集团有限公司 一种玻璃退火窑侧墙保温棉模块化填充方法
CN103395975B (zh) * 2013-07-31 2015-08-12 中国建材国际工程集团有限公司 一种玻璃退火窑侧墙保温棉模块化填充方法
WO2016012860A1 (fr) * 2014-07-24 2016-01-28 Sabic Global Technologies.B.V. Acier laminé à froid recuit et son procédé de préparation

Also Published As

Publication number Publication date
CA1315540C (fr) 1993-04-06

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Effective date: 19970326

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